RDFa Core Initial Context

This list of predefined prefixes have been defined for RDFa as an “initial
context”: essentially, RDFa users can use these prefixes without
having the obligation of defining the prefixes in the HTML code. The
same list of prefixes have also been defined for JSON-LD as a JSON-LD
Context at the URI http://www.w3.org/2013/json-ld-context/rdfa11;
JSON-LD users can use the @context key with that URI as a
shorthand to use the same prefixes.

Some vocabularies are currently in development at W3C and they may
become W3C Recommendations or Notes, i.e., may become part of the table
above. It is therefore advisable to consider their prefixes reserved for
now. These are: